To date, the adhesives for binding layers or films made of PE or made of polyester were based on ethylene/alkyl (meth)acrylate and/or ethylene/vinyl acetate copolymers. However, these adhesives have the disadvantages of giving off a strong smell, which presents operating problems. Moreover, their adhesiveness is not in particular very effective and, in any case, not in duration. These adhesives also have the disadvantages of not allowing the adhesion of polyester or polyolefin layers to EVOH (barrier material) layers.
The document FR 2 806 734 of the Applicant Company discloses a composition comprising metallocene PE and non-metallocene LLDPE which are cografted with unsaturated carboxylic acid or its derivative, said composition being diluted in PE or an elastomer. The PE being able [sic], in this application, to be a PE homopolymer or copolymer with, in this case, an α-olefin for comonomer and it can be a PE of HDPE (high density PE), LDPE (low density PE), LLDPE (linear low density PE) for VLDPE (very low density PE) type or a metallocene PE. No information or examples are given with regard to the diluent when the latter proves to be metallocene PE.
The Applicant Company has now found a tie which no longer presents olfactory problems like the ties of the former generation and which exhibits a significant adhesiveness from its application which increases until a plateau is reached. Furthermore, this adhesive adheres to EVOH (barrier material) layers, contrary to the adhesives of ethylene/alkyl (meth)acrylate or ethylene/vinyl acetate type.
This tie exhibits adhesion characteristics which are not described in the other documents of the prior art. These characteristics are described later in the present document.
The tie is recovered in the form of granules at the outlet of an extruder or of any other equivalent device; the Applicant Company has found that this granulation was much easier than for the ties of ethylene/vinyl acetate type which are grafted.
This tie thus makes possible the preparation of varied structures comprising, inter alia, a polyethylene layer, a polyester layer and/or a barrier material layer. A person skilled in the art will adapt the choice of the polyester according to the conversion method chosen.
These structures are of use in the manufacture of flexible or rigid packagings, such as bags, bottles, containers, pipes, coextruded hoses, or multilayer gas tanks for vehicles.